Machine and method for making wall board



I'AGHINE AND ITHon vonA MAKING WALL BOARD 'Filed Dec. 22, 1927 "if v lNvgNTron Max' /f/ze pt h .BY/Dwell 0M,

ATTORNEYS Patented l Nov. 3, 1931 UNITED STATES PATENT OFFICE MAX OF MADISON,I WISCONSIN, ASSIGNOR T C. F. BURGESS a IN C., OF MADISON, WISCONSIN, A CORPORATION OF DELAWARE I'ACH'INE .AND MIETEOD FOB- MLKINGWALL BOA-'BD Application-tiled December 22, 1927. Serial No. 241,765.

My invention relates to a machine for makel object of my invention is to construct va machine which is adapted to continuously make wallboard with the minimum amount of labor and waste. Further objects and advantages will be apparent from the followin description.

n a `co-pending application of Kemper Slidell, Serial No.1103,213, filed April 20,

1926, (now Patent Number 1,655,714 granted f January 10, 1928) there is disclosed and claimed a machine and method for making wall board of this type. In the Slidell mal chine the paper faclngs and raw mix are passedl between heated platens to form the board and give it an initial set, then through a heat-treater to dry and harden it, and then through pull rolls by means of' which it is drawn throu h the machine. If the boards are passed directly from the platens to the pull rolls, they are not suiiciently hard to stand the pressure of the rolls and are crushed. v

I have found that if a hardening chamber' is placed behind the platens and the board hardened before it is assed-through the heat treater, the pull ro ls may be arranged infront of the heat treater without injuring the board as it passes through said rolls. The arrangement' of the pull rolls in this position permits certain 'economies and flexibility in operation not ,possible in ythe Slidell machine. f

In the, Vaccompanying drawings I have shown several forms of apparatus capable of use in practicing the process 'of my invention.

Fig. 1 is a diagrammatic side elevation of 011e form of apparatus, and

Fig. 2 is asimilar view of another form of apparatus.

My, invention' applies especially t0 Wall boards and similar structures made by putfing by heat a doughlike mixtureoff' .alkali 1type the mix is usually silicate and ller. The heat treating apparatus mayalso be used for boards made with an alkali silicate and filler core but which are not puffed. In wall boards of the puffed ulfed between two facings, vsuch as chip board liners. The doughlike mix is made of about one part of alkali silicate, such as sodium silicate, and about two parts of powdered filler, which nayll? dolomite, limestone, slate,jashes, and t e i e.

This doughlike mix is ro led between the two facings to the pro r thickness after which it is subjected to a eating operation, preferably between steam heated platens. The sudden vaporization of the water contained in the doughlike mix containing sodium silicate causes a uing action which results in a porous brea ike structure. The rapid escape of the steam soon causes the structure to harden. This heat treatment may be continued to dehydrate the silicate still further and thereby make it more water resistant. By using higher temperatures than are practical with steam, improved results'are ob tained, this procedure requiring a secondary heat-treating operation. My a paratus and method contemplate the use o? such a secondary heat-treater.

In accordance with my present invention the operations of pulling, hardening and subsequently heat-treating the board may be carried out in the apparatus of Fig. 1 or 2, Referring specifically to Fig. 1 of the drawings, the doughlike mix may be placed in a hopper 1 arranged above a pair of rolls 2. Suitable facings or liners 3 and 4 may be fed from conveniently arranged windes and threaded through .the rolls 2. The mix, as is leaves the hopper, is squeezed between the facings to a predetermmed thickness,\ dependent upon the desired weight and thick- To this a small amount of soap. usually is added to hel the pung action.l

LABORATORIES,

ness of thefinished board, which mayy be regulated by adjustment ofthe rolls 2. The

sides of the hopper are spaced from the edges of the facings and from the endsv of the rolls 2 so that the doughlike mix willl not squeeze wires 5; From the squeeze rolls 2 the board passes through a puffing apparatus 6, a hardv ening chamber 7 and a heat-treater 8'. When the boards are submitted to a hardening operation lmmedlately after they have been given `an initial set in the puffing apparatus, they may be pulled through the apparatus by pull rolls 9 arranged in front of the final heat-v l treater 8. The board is pulled .through'the apparatus at a rate Which allows it to be subjected to the required treatments for the proper length of time. The surface speed of the squeeze rolls 2 should be about equal to the surface speed of the pull rolls 9 sothat the green board between the squeeze rolls and in the puffing apparatus is neither subjected to too much tension nor becomes too slack.

The puiingapparatus 6 consists of a series of-heated vplates or platens accurately machined on the surfaces exposed to the board.

The plates are spaced apart accurately ata distance slightly greater than the finished thickness of the board because, fortunately,

the board shrinks slightly after reaching a maximum thickness during the first violent pufling reaction due tothe sudden formation of steam. The facings are confined by the platens and the pressure, strange as this may seem', is not great enough to cause excessive friction between the `moving facings andthe confining platens. The friction of the board sliding through the platens is further reduced p by using polished platen surfaces. The spacing of the platens is regulated -by means of screws 11 working in brackets l2 attached to the-platens. rIhese may be used to release the board -in case of sticking. The 'platens may be heated in any convenient way, as by various fluids. The fluids may be eitherliquid or gaseous, such as steam, air, gases of combustion, oil, water, molten salts and metals. Electricity may also be used.

As the green board is rapidly heated to above the boiling point of water, the moisture in the mix is volatilized and escapes through the edges of the board, at the same time pressing the facings aga-inst the platens. If the doughlike mix is of the correct composition and consistency it puffs without appreciably blowing out at the edges, and does not collapse after `the steam has escaped.

' After the large part of the steam escapes, the board has set and is hard'enough to handle.

During the puffing operation vthe board is puffed suiiciently to set the porous structure, but it is not then hard enough to` permit it to be passed through the pull rolls 9 Without linjury. Furthermore the residual moisture must be removedsfrom the porous structure to. render it highly resistant to moisture.

after leaving the ,pulling apparatus, I prefer toY side trim the hot` freshly formed board with sideI cutting saws 13. These saws are `preferably carborundum discs running` at gh speed'. The board is cut Wider than the bevcut ations. By placing the side trim saws 1n this position the board is cut or trimmed before hardening when the saws will readily cut it and will not be subjected .to excessive Wear in the 'cutting operation.

After side trimming, the boardsare passed through the hardening chamber 7 which should be heated to a temperature at least as high as the temperature of thefpung platens and can be heated to a higher temperature so as to drive the heat through the boards'. In the hardening. chamber I mayv employ platens similar to the platens in the pulling apparatus, or the hardening operation may be accomplished by means of heated air or other gases. The hardening operation may be efliciently performed by submitting the boards to a temperature of 120 C. or more for a period of-not more than live minutes. Upon leaving the hardenin chamber the boards may be passed'tnroug the pull rolls .9 without injury and the board is fed through the The heat-treater 8 preferably is essentially Thence itpasses to the heat-'treater 8' an insulated tunnel through which the puffed board passes. The board may be untrimmed or side trimmed and is subjected to 'a predeterminedtemperature for a'deinite length of time to secure the proper moi' ture or water resistance. The board shoul be subjected toa temperature of about 210 C. or more for about twenty minutes or more.` This insures satisfactory results for a 3/8 board. The heating shoiild be long enough to penetrate through the board pends on the thickness. lThe length of time of heating at about 210 C. or more and the upper temperature is limited by the danger of discoloring the facings due to scorching.

and therefore de- While any suitable method of heat treating i may be used I prefer using hot gases, especially hot gases of combustion. In my continuous heat-treater, both surfaces of the wall board'are directly7 vexposed to the hot gases. Thev trimmed e ges expose the porous structure, thus allowingthe moisture, which, is'driven off by the .high temperature, to escape easily. I prefer to have the gases pass overthe board at a high velocity in a -direction o posite to the travel of the board so that the iiottest gases 'come in contact with the hottest portion of the board. After passing through to length by suitable cutting apparatus 14.

In the form of apparatus shown in Fig. 2 of the drawings, the green board is formed in thesame manner and is passed through similar pulling apparatus .6. The construction and method of procedure with respect to ,theside trim saws 'and the hardening the heat-treater the boards .may .i

fore they are given the final heat treatment and employing a multiple deck dryer, economy in heat may be obtained as the length of the dryer can be greatly reduced for a plant of a given capacity. The individual sections of board will remain in the dryer :for a longer period'of time as the various decks of the dryer will be successively loaded and emptied. Suitable means 17 may be employed for receiving the boards from the various decks of- Q one part of a' high viscosity sodium silicate,

two parts of finely ground limestone, which may be dolomitic in character,l and about ninety-five percent of which would pass through a 200 mesh screen, with less than one percent of a soap-forming acid, such as oleicacid, and starting with chipboard liners .037 thick, and of normal moisture content, and with the press rolls 2 adjusted to yield a finished board 'f5/8'. thick, the pufiing appa-' ratus is maintained at atemperature of 120 C. to 170 C. and the time of transitV of the board through the putling apparatus is about eleven minutes. The hardening chamber may be maintained at a slightly higher temperature and the boards are passed through the hardening chamber in a period of about two minutes, and not more than five minutes. The time that the board remains in the hardening chamber will vary according to the temperature maintained therein. In the heat treating chambers 8 and 1 5 a temperature ofabout 210 C. is maintained and the boards are submitted to this heat treating operation for a period of from twenty to twenty-five minutes. The foregoingis but illustrative and I am aware that radical departures can lbe madev nation', means for-rolling a dough-like mix of filler and alkali silicate between two continuous facings, means for pufiing said doughlike mix, means for continuously trimming the edges ofsaid puffed mix and facings, means for hardening the board so trimmed, means for pulling said board through said pulling means, said trimming means and said hardening means, means for cutting said board to suitable lengths and means for heattreating said cut boards' while still hot, said hardening means beingA intermediate said puiiing means `and -said final heat treating means.

2. In a machine for making wall board, the l combination of means for continuously shaping an intumescent plastic between continuous covering sheets of paper, means for intumescing said plastic to give it an initial set, means for side-trimming the initially-set board, heating means to initially harden said board, means for pulling said board through said intumescing means, said trimming means, and said hardening means, and means for heat-treating said initially-hardened board` said hardening means being intermediate said pufiing means and said final heat treating moans.

3. In a machine of the character described, the combination of means for shaping a' plastic of alkali silicate and filler between continuous covering sheets, means for intumescing said plastic and giving it an initial set, means ["or continuously trimming the edges of the faced, initially-set-,vintumesced plastic board, heated platens between which the trimmed board may pass, said platens being hot enough to initially harden said intumesced plastic, pulling rolls for pulling said board through said intumescing means, said trimming means, and said platens, and means for cutting said initially-hardened board into suitable lengths while still hot said hardening means being intermediate said puffing means and said final heat treating means.

4. In a machine for making wall board with a layer of mixed alkali silicate and filler puii'ed and hardened by heat and held between paper liners, the combination of putfing means,- trimming means, and pulling rolls, a hardener intermediate between said trimming 'means and said pulling rolls, and heat-treating apparatus beyond said pulling rolls to receive. the board while still hot.

5 In a machine for making wall board with a layer of mixed alkali silicate and filler puffed and hardened by heat and held between paper liners, the combination of a hardener between the puiiing means and pull rolls, cut-off mechanism beyond said pull rolls and means for heat-treating said board while still hot.

between side-trimming saws and pull rolls.

7. In a machine of the character described,

the combination of a platen liardener intermediate between side-trimming saws and pull rolls.

8. In a machine of the character described,

5 the combination of pull rolls between a hardening chamber and a heat-treating chamber. 9. The method of making wall board which comprises continuously shaping an in-y tuinescent plastic between covering sheets of paper, then quickly intuniescing and settiiior said plastic by heat, then side trimming sai Y initially set board, then quickly hardening lsaid board by heat, and then subjecting the liot, initially hardened product to a tempera- I 15 ture high enough to render said intuinesced and hardened material highly resistant to moisture.

10. In a machine of the character described the combination of a hardener intermediate 2 the puffing means and final heat treating means.

1l. The step in the method of making wa'll board comprising a mixture of alkali silicate and filler puffed by heat, which 4comprises hardening hot, initially-set, intumesced-wall board .sufficiently to resist the crushing action of pulling rolls prior to the final heat-treatnient of said boaid.

.12.'iThe-steps in the method of making Wall board comprising a mixture of alkali 40 quickly hardening said mixture sufficiently,

' lafter being initially set in the puiiing operation, to resist the crushing action of subsequent frictionally engaging pulling rolls, cutting the hot hardened board into suitable lengths and immediately heat-treating said board while still hot to render it highly resistant to moisture.

14. The method of hardening a faced, initially-set, inti'imesced-plastic Imixture. of alkali silicate and filler which comprises expos- .ing it While still hot and prior to nal heat treatment of said board to a temperature at least as great as the intumescing temperature for not more thanve minutes.

15. The method of hardening a faced, initially-set, intumesced-plastic mixture of al--I kali silicate and'filler, which comprises heating it While still hot and prior to final heat 6 treatment of said board between platens heated to a temperature at least as great as the intumescing temperature fornot more than five minutes. f'

v 16. YThe method of hardening a faced, ini- I tially-set, yintumesced-plastic mixture of alkali silicate and filler which comprises heat-v ing it While still hot and prioi to the final heat-treatment of said board to drive ofi' sufficient moisture so that said mixture will resist the crushing action of pull-rolls.

17. 'Ihe steps in the method of making wall board-comprising a mixture of alkali silicate and filler puffed by heat' comprising intumescing said board by heat sufliciently to give it an initial set and then quickly hardening said hot initially set board byv heat prior to the final heat treatment of said board.

18. In ainachine for forming sheets from plastics, the combination with a pair of heated platen walls of substantial area, means for. feeding. plastic material between` said Walls, a hardening oven associated with the platens and closely adjacent thereto, a drying and curing oven, and a feeding device l0- cated between the two ovens adapted to draw the hardened sheet from the first and to movev it into the second.

19. Ina machine for forming sheets from plastics as a continuous process, the combination with a pair of heated platen walls of substantial area, means for feeding plastic inaterial between said walls, a hardening oven associated with the platens and closely adjacent thereto, a drying and curing oven, a severing device located between the two ovens to divide the continuous sheet into lengths and a feeding device also located between the l ovens and adapted to draw the sheet from the first and to move the severed sheets into the second.

20,'In a machine for forming sheets from plasticsas a continuous process, the combination with a. pair ofheated platen Walls of substantial area, means for passing a lining sheet between said walls, means for supplying intumescent plastic material between the platen walls `in contact with the lining sheet to be puffed and cemented-to the liner surface by the `action of the platens, a hardening oven associated With-theplatens and closely .adjacent thereto, a drying and curing oven, and a feeding device located between the ovens adapted to draw the liner and the adhering hardened body of material from between the platen walls and thence through the v hardening oven and to push it into the drying and curing oven. e 21. In a. machine for forming sheets from plastics, the combination with a pair of heat- Y ed platen walls 'of substantial area, means for feeding plastic materialbetween said walls, a hardening oven associated with the platens and closely adjacent thereto, a drying and curing oven, and a feeding device located between the two ovens adapted to draw the hardened sheet from the rst and to move it into the second, the sheet carrying capacity of the drying and curing oven per lineal foot of its length being greater than that of the said hardening oven.

22. In a machine for forming sheets fi'oni plastics, the combination with a pair of heated platen walls of substantial area, means for feeding plastic material between. said walls, ahardening oven associated with the platens and closely'adjacent thereto, a drying and curing oven, and a feeding device located between the two ovens adapted to draw the hardened sheet Ifrom the rst and to move it into the second, the said second drying and lo' curing oven being a multiple deck oven rovided with means for delivering the pro uct Y to diferent decks thereof. 23.- In a machine for forming sheets from plastics,l the combination with a pair of heated platen walls of substantial area, means for feeding plastic material between said walls, a hardening oven associated with the platensand closely adjacent thereto, a drying and curing oven, a feeding device located between the two ovens Aadapted to draw the `hardened sheet from the first' and'lto move it into the second, and a severing device in rea-r of the feeding device adapted to cutthe product into separate sheets, the said second drying v -and curing oven. being a multiple deck oven provided with means for passi-n such sepa-l .rate sheets of `the product to di erent decks thereof.

I v Intestimony whereof I aiix 1n si ature.

I so, 

